Today, infectious animal diseases are a major cause of morbidity and mortality in Los
Angeles County. These diseases will persist beyond our life-times, therefore prudent
measures must be taken today to prevent and control disease tomorrow. Controlling disease
now reduces our future health expenditures. Treatment of end stage disease can be very
expensive and may not be effective.

Close agreement on the importance of surveillance and an active, trained work force to
control disease exists among public health professionals. Disease
surveillance/prevention/control requires a solid foundation in basic detection and control
measures. Wishful thinking and expressions of concern have no impact on disease. Control
of disease can be accomplished only through concrete, specific actions geared toward
protecting the community as a whole.

There are more than 200 diseases of animals transmissible to people (zoonoses)
currently causing a wide variety of human illness. In addition, as yet undefined zoonotic
diseases probably exist that pose infectious risks for people. The Institute of Medicine
reported on various factors implicated in the emergence of infectious diseases within the
United States and insisted that, "The significance of zoonoses in the emergence of
human infections cannot be overstated." Effective control of many human zoonoses
first, or concomitantly, requires control in animals. The role of simian immunodeficiency
virus, which is closely related to human immunodeficiency virus-2 presents fertile
territory for speculation and investigation.

These emerging, infectious diseases illustrate why an effective surveillance system is
vital to community disease control. An early warning mechanism gives local authorities
time to put control measures into effect to reduce the community's health care costs. The
development of a proactive approach to public health includes having trained staff who can
quickly enact control measures.

The world is becoming smaller as we approach the twenty-first century. We increasingly
find that our neighbor's disease problems become ours. This is particularly true in Los
Angeles County with such cultural and animal diversity.

Animals as Sentinels

Over 100 years of experience has shown animal and human health are closely related.

Like people, domestic animals and wildlife are exposed to infectious diseases and
environmental contaminants in the air, soil, water, and food and they can suffer from
acute and chronic diseases from such exposure. Often animals serve as disease sentinels,
or early warning systems, for the community.

Some advantages of using animals as sentinels include: lower cost, shorter latency of
disease development and greater ease of obtaining tissue samples and autopsy data.
Sentinel animals have shorter life spans than people and diseases with long latency
periods will manifest themselves in sentinel animals before people. To understand what is
happening in animals requires regular and systematic analysis of data to identify health
hazards. Sick animals can alert people to environmental dangers just as a barking dog
alerts its owner of an intruder.

Animals can also reveal health hazards associated with environmental pollution.
Environmental diseases are highly preventable causes of morbidity and mortality. The
classic example was the use of canaries in mines. The simplicity of the system exemplifies
the ease with which some animal sentinel systems can be used.

In the 1950s, Japanese veterinarians recognized "dancing cat fever" in local
cats in the fishing village of Minimata, then a similar disease appeared in fishermen and
their families. Investigation revealed the source of the outbreak to be mercury poisoning
in locally caught fish. Fish off the coast of Los Angeles are contaminated with DDT. Since
1965, birds have been used for an indication of pesticide contamination in the United
States.

In Chicago, a study during the 1970s revealed that children who lived in households
with dogs that had high blood concentrations of lead were six times more likely to have
high blood lead concentrations themselves.

Reportable Diseases

The director of health services is accountable for all reportable human diseases in Los
Angeles County. Since 1972, the director is also accountable for all reportable animal
diseases. Medical practitioners are legally required to report such diseases to the local
health authorities, who in turn are required to investigate the reports and take whatever
action is necessary to control the disease. Generally, any person having knowledge of any
disease outbreak, or the occurrence of a case of an unusual disease, shall promptly notify
the health authorities. Such a reporting requirement of sentinel cases is crucial if we
want to effectively control disease. Disease containment requires the ability to determine
the cause of disease, or death, so a logical approach to control can be taken.

Zoonoses

In California, over 45% of human diseases reportable to the California Department of
Health Services are zoonoses (table 1). In 1997 it was confirmed that the prion causing
bovine spongiform encephalopathy (mad cow disease) is also responsible for atypical
Creutzfeldt-Jakob disease (CJD). This expands the list of zoonoses. In 1996, with the
report of seventeen cases of atypical CJD, it was suspected the patients obtained the
infectious prion from eating contaminated beef. Since first recognized in 1985, mad cow
disease has caused the destruction of over a million cows in Britain The cows were exposed
to the infectious agent in their food which had been contaminated with protein from sheep
infected with scrapie (ovine spongiform encephalopathy). Twenty people in the United
Kingdom have the new CJD variant and one person in France. All but one are dead. There is
no known treatment for the disease in people or animals.

These neurodengerative diseases of people and animals have prolonged incubation
periods, the appearance of widespread spongiform changes in the brain and production of an
abnormal protein. These disorders were originally called subacute transmissible spongiform
encephalopathies or slow virus diseases. There is no apparent antibody or cell-mediated
immune response to the transmissible agent. The transmissible agents are resistant to
commonly used physical and chemical inactivation methods or ultraviolet irradiation. In
the United Kingdom, construction of massive incinerators were required to properly dispose
of all the infected dairy cattle. Today, these diseases are called prion diseases and are
seen in cattle, elk, mink, mule deer, people, and sheep.

In 1997, Lancet reported CJD, which was associated with consuming
squirrel brains in people in Kentucky. In rural Kentucky, people scramble squirrel brains
with eggs or put them in stews. This observation requires confirmation by studies of
larger populations and a search for a prion agent in the brains of squirrels.

In California, of animal diseases reportable to the California Department of Food and
Agriculture (table 2) over 40% are zoonoses. Some zoonotic diseases on the two lists of
reportable diseases over lap. Examples of such diseases include: anthrax, brucellosis,
encephalomyelitis, erysipelas, listeriosis, rabies, and tuberculosis. There are other
reportable animal diseases that occur in people and would be reportable to the health
officer under Section 2503 - Occurrence of unusual diseases. Any person having knowledge
of a case of an unusual disease not listed in Section 2500 shall promptly convey the facts
to the local health officer.

There are also diseases of people which are transmissible to animals and such diseases
are referred to as reverse zoonoses (table 3). Some of the more common reverse zoonoses
are in table 3. Los Angeles County's most recent outbreak of reverse zoonoses started in
1996 with the death of two circus elephants with extensive tuberculosis (Mycobacteria
tuberculosis) involving over 80% of their lungs. This year an elephant with
tuberculosis (Mycobacteria tuberculosis) died at the Los Angeles Zoo and a second
one with tuberculosis was transferred to the San Francisco Zoo. This month the Los Angeles
County Public Health Laboratory confirmed Mycobacteria tuberculosis in eight
different elephants. Regulations to control the spread of tuberculosis in elephants are
under development.

Table 3 Reverse Zoonoses

Examples of infectious diseases of people occasionally transferred to animals and
transferred back to people. Recently termed reverse zoonoses.

AGENT

HUMAN DISEASE

ANIMAL DISEASE

ANIMALS

Mumps virus

Mumps

Parotiditis

Dogs

Infectious hepatitis

Hepatitis

Hepatitis

Nonhuman primates

Corynebacterium diphtheriae

Diphtheria

Ulcers on teats, mastitis

Cattle

Staphylococcus aureus

Furunculosis

Furunculosis, mastitis

Cattle

Streptococcus pyogenes

Pharyngitis, scarlet fever

Mastitis

Cattle

Giardia lamblia

Nausea, flatulence, diarrhea

None known

Beavers

Mycobacteria tuberculosis

Tuberculosis

Tuberculosis

Deer, dogs, elephants

Zoonoses in Wildlife

People contact zoonoses from interaction with bats, birds, insects, opossums and
rodents to name a few. Forty-two wildlife diseases that people can catch are listed in
table 4 in the appendix. Malaria is a classic example. It halted the first attempt to
construct the Panama canal. The canal is an engineering marvel and a triumph over wildlife
disease.

Wildlife Disease Defeats the French

Actual construction of the Panama Canal began in 1882 by a French
company. During seven years of digging, 22,000 men died of tropical diseases. This was
equivalent to wiping out the entire construction crew twice, for the total number of men
employed at any one time did not average more than 10,000.

The French canal builders did not know deadly malaria and yellow fever were caused by
bites of certain mosquitoes. Mosquitoes and people serve as reservoirs for human malaria.
Malaria also infects birds and lizards and monkeys. Jungle yellow fever infects monkeys.
Serious errors were made in sanitation. French physicians were said to have ordered the
legs of hospital beds placed in water to keep ants and other crawling bugs from the
patients. The water became an additional breeding place for mosquitoes, which already were
swarming in from marshes, streams, and pools in the hot, rainy region. The French
abandoned their efforts.

United States Conquers Disease and Builds the Canal

During the Spanish-American War in 1898, the U.S. Navy sent the battleship Oregon
from San Francisco to Cuba to reinforce the Atlantic fleet. The 13,000 mile trip around
the tip of South America would have only been 4,600 miles through a canal. This convinced
Congress that a canal was essential for national defense.

In 1902 the United States agreed to buy the concession of the French company for 40
million dollars. The United States paid Panama 10 million dollars plus 250,000 dollars a
year for the use, occupation, and administration of a 10-mile-wide strip along the canal,
5 miles on each side. The United States took possession of the canal property on May 4,
1904.

The greatest obstacle to building the canal were the tropical diseases jungle yellow
fever and malaria, for which there were no cures. Malaria comes from two Italian words
that mean bad air. People gave the disease this name because of its association
with the musty, bad-smelling air of swamps. Deaths of howler and spider monkeys in the
forest in Central and South America was common with yellow fever. Two medical discoveries
allowed the project to succeed. It was determined that malaria is transmitted by the bite
of the Anopheles mosquito.

In 1900, Dr. Walter Reed, of the U.S. Army headed a commission to investigate an
epidemic of yellow fever among American troops in the Spanish-American War. He and other
physicians conducted a series of daring experiments in which several physicians and
solders volunteered to be infected with the disease. Two died as a result. The experiments
proved yellow fever was transmitted by the bite of mosquitos.

The first 2 ½ years were devoted to the careful preparation
that brought health and efficiency when actual construction started. Proper sanitation and
mosquito control made the Canal Zone safe for men to live, raise their families and work.

Every lake, swamp, pond, and ditch that could be emptied was drained. Over those that
could not be drained, a film of oil was spread to destroy mosquito eggs and larvae. All
buildings above the ground were raised. Windows, doors, and porches were screened. People
covered every vessel that held water. All railway cars were screened, and a hospital car
was added to every train. Cities were given sewers and pure water. By 1906, yellow fever
had been wiped out in the Canal Zone. By 1913, malaria was greatly reduced. In 1914 a ship
made the first complete trip through the canal.

Zoonoses in Domestic Animals

Historically it has been shown that as zoonoses increase in animals it spills over into
the human population. Man working with domestic animals comes into contact with zoonoses
routinely. For the prion and viral diseases there is no effective treatment. Several of
the bacterial diseases may be resistant to antibiotics. Effective treatments exist for
some of the protozoan and metazoan diseases.

A variety of domestic animals are capable of transmitting disease to people including:
cats, cattle, dogs, horses, poultry, sheep and swine. Forty-two examples are listed in
table 5 in the appendix. Cat-scratch fever,
Malignant pustule, Milker's nodules, Wool sorters disease, Q fever, and ringworm are lay
terms for some of the diseases. Three diseases - anthrax, psittacosis, and salmonellosis
will be briefly discussed.

Anthrax has been recognized as an infectious disease of people and
animals for centuries. It was common in Rome during the last five centuries BC. In
nineteenth century Europe, 20% to 30% of sheep and cattle died of anthrax each year.
Sudden death is common in domestic livestock. The organism is found in the soil. Today, in
anthrax areas, livestock is vaccinated against the disease.

Today, aerolization of anthrax by terrorists is of major concern. The death rate for
untreated anthrax is over 90%. Anthrax is one of the common biological agents thought to
be favored for use by terrorists and disgruntled citizens. Anthrax threats have become
rather common in the United States. For example, in December of 1998, four threats
alleging use of anthrax were reported in the greater metropolitan Los Angeles area. All
were hoaxes.

Psittacosis was described 100 years ago and is caused by an
intracellular bacterium Chlamydia psittaci. All birds may be infected.
Psittacosis is a common occupational hazard to workers in the pet bird industry and
turkey-processing plants. Sporadic cases are commonly associated with ownership of pet
birds. As a public health measure, all imported psittacine birds are placed in quarantine
and placed on chlortetracycline feed for 30 days. In California, all parakeets are
required to undergo treatment and are leg banded. The leg band allows an infected bird to
be traced back to its origin.

Salmonellosis is a bacterial infection in people often related
directly or indirectly to infection in animals. In 1975, the small pet turtle was the most
common source of salmonellosis in the United States. Today in California, it is illegal to
sell turtles with shells of less than 4 inches. Pet iguanas have recently
become a common source of salmonellosis of people. Salmonella is often found on the
surface of freshly laid eggs. Pasteurization of bulk egg products has controlled this
problem.

Animal Populations 1974 - 1997

Between 1974-97, shifts have occurred in various animal populations in Los Angeles
County (table 6). Livestock (cattle, sheep, poultry) once widespread, exist at very low
numbers due to urbanization and the increase in land values. Traditional livestock
(cattle, sheep, hogs, poultry) were replaced with "innovations" in agriculture
(pot bellied pigs, ostriches, llamas, emus, miniature horses, etc.). In 1994 the horse
population peaked at 150,000 and then began to decline as property values continued to
rise.

Interestingly, attendance at the County fair, held in September in Pomona, has
increased slightly from twenty years ago. It remains the largest fair in the nation, with
livestock from all over the country entering the various shows. During this time, the
human population has increased by over one million people and the companion animal
population has increased proportionately to the human population.

Wildlife adapting to urban life and food supplies have increased their numbers. The
opossum, a non-native species, has adapted to urban living and presents difficulties for
animal control agencies. One of the major reservoirs of endemic typhus in Los Angeles
County is the opossum. Several thousand coyotes are picked up by the Department of Animal
Regulation in the City of Los Angeles annually. In the foothill regions, pet cats and
small dogs may provide a food source for coyotes. Mountain lions have increased in the
wild and now are viewed as a threat to people living in the foothills.

The County contains several wild animal compounds housing wildlife sometimes used in
the movie and entertainment industry. Wild animal compounds may also house injured or
abandoned wildlife, which may be rehabilitated and returned to the wild. Since 1974, the
number and size of wild animal compounds holding native and foreign animals has increased.
For example, the largest animal compound, Wildlife Waystation, was formed in 1976 and
today houses more than 1,000 animals (local wildlife and wildlife foreign to the United
States) on a 160-acre wild animal compound in the north end of the San Fernando Valley.
Also about 2000 animals a year use the Waystation as a pit stop before being set free in
the wild or being shipped to zoos. These compounds present a potential exotic animal
disease threat to our domestic and wild animal populations.

The Los Angeles Zoo, the largest zoo on the west coast, has more than doubled its
exotic animal population (lions, elephants, zebras, gorillas, giraffes, camels, etc.)
during the past twenty years. In 1994, the Los Angeles City Zoo contained over 1,300
animals (350 different species) in 130 exhibits located on seventy-five acres. Twenty
years earlier, the zoo's total population was 626 animals. The zoo continues to expand.

Companion Animals

Los Angeles County has over 2.6 million privately owned cats and dogs. There are over
1,000 pet stores in Los Angeles County. Our population of companion animals continues to
increase with approximately one person in five owning at least one animal. Many of these
animals have intimate contact with their owners, increasing the possibility of
transmission of animal diseases to people. Los Angeles has the largest human population of
any County in the nation with close to nine million residents.

Animal Control agencies process over 5,000,000 animals yearly. Most of the animals
processed by these agencies are homeless cats and dogs and about sixty-five percent are
euthanized.

To care for this expanding animal population, the number of veterinarians in Los
Angeles County has more than doubled in the past twenty years. Most of the veterinarians
are in private, companion animal practice. Today, of the licensed California veterinarians
residing in the State, one in five live in Los Angeles County.

Exotic Pets

In August of 1997, a West Hills woman's dog was devoured by a twenty-five pound, seven
and a half foot Boa. The snake, which slithered into an enclosed patio, nabbing the
Chihuahua, raised community concerns about the hazards of exotic pets. In Los Angeles,
over ninety percent of the exotic pets are reptiles. In 1995, it was estimated that 7.3
million pet reptiles were owned by approximately 3% of households in the United States.
Reptiles include snakes, lizards, turtles, crocodiles and alligators.

Between 1994 and 1995, health departments in 13 states, including
California, reported human infections with unusual Salmonella serotypes to the Centers for
Disease Control. Many of the individuals had contact with reptiles (lizards, snakes or
turtles). Salmonella sp were isolated from 36% of the reptiles cultured during
surveillance activities in pet stores in Los Angeles County in 1993.

Changes in Animal Populations = Changes in
Disease Patterns

As animal populations have shifted so have disease patterns. New diseases have been
introduced into Los Angeles County. In 1992, the County experienced the worlds first
epidemic of canine distemper virus in exotic cats with seventeen lions, tigers, leopards
and jaguars dying. Half of the deaths occurred among African lions. Should the virus get
into our domestic cat population, the direct cost of control for the first two years is
estimated at over eighty-two million dollars.

Today, there are more than 100 cases of reptile-associated salmonellosis reported
annually in Los Angeles County. Human salmonellosis associated with lizards was not seen
ten years ago. This increase in salmonellosis is due to the massive influx of green
iguanas being imported from Central America. Iguana farms and wholesalers often use
antibiotics to prevent disease in the lizards, thus increasing antibiotic resistant
strains of salmonella. Iguanas are flown to the southern United States and distributed to
wholesalers. To prevent human outbreaks and associated health care costs, regulations
regarding these reptiles may be warranted, similar to the current regulation of pet
turtles. (Title 17, Section 2612.1).

Public/Private Partnership

A private/public partnership has existed for close to one hundred years in Los Angeles
County, but in times of crisis or disease outbreak, only the government has the authority
to act and regulate the movement of diseased individuals, impose quarantines and require
testing to control and prevent disease spread.

In their role in the partnership, private practitioners have assisted with various
vaccination programs. It was private veterinarians who donated their time to run the first
Southern California Veterinary Medical Association public rabies vaccination clinics for
dogs in 1956. Again, it was private veterinarians who came forward to assist in the
massive emergency vaccination of horses in 1971 when Venezuelan sleeping sickness entered
the United States from Mexico, killing thousands of horses and hundreds of people,
creating a national disease emergency. Within five months, over ninety percent of the
horses were vaccinated in Los Angeles County. A vaccination rate of seventy-five percent
was needed to contain the epidemic.

Food borne Disease

More than 250 different diseases have been linked to contaminated food or drink in the
United States. Tainted food causes an estimated 6.5 million to 33 million illnesses and
9,000 deaths annually in the United States. Many food borne illnesses are traced to poor
animal husbandry and diseased animals. Veterinarians are the experts in animal health and
it is logical they become involved with such outbreaks. The recent record-setting recall
of twenty-five million pounds of Hudson Foods Inc.'s hamburger due to the deadly 0157
strain of E. coli illustrates the impact of food-borne zoonoses.

Food borne disease in the United States may increase with the expansion of free-trade
agreements. In the past five years, food imports into the United States have doubled to 30
billion tons and are expected to keep rising. Mexico ships 90% of its $4.5 billion in
annual food exports to the United States. Argentine beef, banned for seventy years, is now
entering the United States.

The 1992, the California Department of Health Services evaluation of Los Angeles County
Department of Health Service's use of veterinarians advised that veterinarians should be
utilized in the investigation and control of food borne illness traced to animals and
animal products. This includes dairy and poultry products.

Animal Importations

Los Angeles County is the nation's largest port. Over 99 percent of the live animals
imported into Los Angeles County come through the Los Angeles International Airport. Los
Angeles imports more exotic animals for the pet and zoological trade than any other port
in the United States. Foreign animal importation presents the County with potential
disease problems. If diseased animals entering Los Angeles County present a threat to the
animal population, the Department of Health Services is to make recommendations to the
Board of Supervisors regarding control of the situation.

Importation of animals led to the massive foot and mouth disease outbreak in 1924 and
the second outbreak in 1929. A Newcastle disease epidemic was imported into Los Angeles
County during 1972 in which over four million animals died. Los Angeles's last rabid cat
was imported through Los Angeles International Airport.

Types of exotic animals imported vary depending on popularity and fads. For example,
reptiles are now the most popular exotic pet in Los Angeles. Since most fashionable
species will not breed in close confinement, they are captured in the wild and imported.
In the United States, poachers steal reptiles from protected areas such as National parks.
The number of reptiles imported into the United States has increased dramatically in the
past ten years, due mainly to a 100 fold increase in the number of iguanas imported into
the United States. Over 200,000 iguanas, generally the green iguana, were imported into
Los Angeles County from 1990 to 1993.

People smuggle animals into Los Angeles County. It is highly profitable and there is
little risk of being caught. If you are caught, the fines are small. Smuggled animals
present disease problems to our human and animal populations. About 500 parrots are
smuggled into Los Angeles yearly. This August, authorities in Lima, Peru, alerted by
barking police dogs, found 1,000 reptiles packed in crates marked "ornamental
fish" which were to be smuggled into Los Angeles. The reptiles were valued at
$500,000.

Animal Shelters in Los Angeles County

Animal control agencies in Los Angeles County process over 500,000 animals every year.
Most of these animals are stray or abandoned pet animals found in the community or turned
in to shelters by citizens. Roughly nine out of ten of the stray animals processed by the
three largest animal control agencies were cats and dogs. About one animal out of four was
placed or purchased. Puppies and kittens were the easiest animals to place. The top three
agencies process over 300,000 animals (dogs, cats, livestock, birds, exotics) yearly and
have a total of 15 animal shelters (Table 7).

The City and the County of Los Angeles, along with Humane Societies and other animal
control agencies, competitively bid for contracts from incorporated cities to handle their
animal control problems. The County of Los Angeles presently contracts with over 35 cites.
Contracts generally cover five years and may include full or partial services.

Animal control agencies also deal with wildlife. During 1996, in the San Fernando
Valley alone, Los Angeles City Animal Regulation officers trapped 2,076 opossums, 192
raccoons, 103 coyotes, 85 skunks, 3 bobcats, and 3 foxes. Mountain lions have been sighted
in the northern foothills of the San Fernando Valley.

Rabies Control

Rabies was first confirmed in the City of Los Angeles in 1898 when an English gentleman
living close to the intersection of Third and Flower Streets informed the health officer
that his dog, who seemed unexplainably nervous and uncontrollable, might have rabies. The
next year, a Pasadena man was bitten on the nose by his cocker spaniel and became the
City's first resident to die of rabies. Prior to 1900, the western states were practically
free of rabies. Coyotes frequented the local dumps and were thought to be responsible for
the rabid dogs. In 1995, Texas declared a state wide quarantine in response to an
uncontrolled outbreak of rabies in coyotes which spread to dogs.

Eight hundred and forty-seven rabid animals, mainly dogs, were detected in Los Angeles
County in 1937. This prompted the formation of the County Pound Department. In 1955,
seventy rabid dogs were diagnosed in the County and fifty-two people were bitten by known
rabid dogs. That year, rabid dogs accounted for one out of every three hundred dog bites.
The following year, Los Angeles County required all dogs within the County be vaccinated
against rabies as a prerequisite for licensing.

California followed the County's lead the next year and required that all dogs be
vaccinated to protect community citizens from the fatal disease. Today, the State of
California requires all Counties which have rabies to maintain an active rabies
surveillance system. Animal bite reporting by physicians and other health professionals is
mandatory. Animal shelters contribute to the enforcement of California rabies control
requirements by providing animal pounds, stray animal control, and rabies vaccination of
animals at their facilities. Rabies investigations and rabies surveillance is done by the
health officer.

California averages over one rabid animal a day, with the vast majority of cases
occurring in wildlife. In 1995, Los Angeles County drastically reduced it's rabies
surveillance and animal bite reporting, but still detects rabid animals (bats) during the
year.